FIELD: electric networks, applicable for protection of the three-phase network with an insulated center-tap from single-phase ground short-circuits.
SUBSTANCE: the state of network insulation and the zero-sequence currents in the outgoing lines are monitored, at a reduction of the network insulation level a circuit is formed for a short-time flow of current of a double short-circuit to ground, the variation of the zero-sequence currents in the outgoing lines is monitored, if at the instant of flow of current of a double short-circuit to ground is varied in one of the outgoing lines, a signal is formed for disconnection of this line because of its ground short-circuit.
EFFECT: enhanced protection selectivity.
1 dwg
